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Archive: May 2017

Congo Red Stain

The ability to detect amyloid deposits in human tissue is the critical first step in making a diagnosis of amyloidosis. David P. Steensma, MD, offers readers a fascinating history of the Congo red stain (see references), which still remains the most widely used and cost-effective way to identify amyloid deposits in pathology specimens. Although reportedly first used to stain human tissue in 1886 (see H. Greisbach), it would not be until 1922 that the dye’s specificity for amyloid would be exploited (see H. Bennhold). And it would be another five years before the well-known “apple-green” birefringence of Congo red-stained amyloid deposits...

Chef Boyardaniel

Chef Boyardaniel is perfecting his cookie recipe* because at this year's River Cities Dragon Boat Festival we are having a bake sale! We'll have various baked goods for sale with all proceeds benefiting the Children's Protection Center- Little Rock, AR. June 17! Come see us! (We totally bought these delicious cookies from Kris & Sam's The Box Lunch and Cookie Store)

Pushing Glass (May 30, 2017)

A 62-year-old Asian male with a past medical history significant for ESRD secondary to hypertension S/P renal transplant (9 months ago) presents with a creatinine of 1.9 (baseline 1.2). The patient has had no previous episodes of rejection. The donor-specific antibody is negative. CMV, adenovirus and BK serology is pending. What is the best diagnosis? A. Acute Cellular Rejection, Banff Type 1B B. BK Nephritis C. Adenovirus D. Acute Antibody-Mediated Rejection The correct answer is B (BK nephritis). The low power trichrome picture shows patchy interstitial inflammation and fibrosis. The glomerulus has thickened capillary walls, but no definitive double contours...

Diffuse Mesangial Hypercellularity

This biopsy is from a previously healthy 3 year old female, who presented with sudden onset nephrotic syndrome, hypertension and microscopic hematuria. Light microscopy shows greater than 4 cells per mesangial region in most glomeruli (Fig 1), with absence of segmental glomerulosclerosis. Immunofluorescence is completely negative and electron microscopy shows diffuse epithelial foot process effacement (Fig 2). The findings are consistent with minimal change disease with diffuse mesangial hypercellularity. This pattern of injury is considered a variant of minimal change disease. Patients with diffuse mesangial hypercellularity have a higher risk of initial resistance to steroid therapy; however, it is not...

Light Chain Cast Nephropathy

Immunofluorescence staining with kappa light chain and lambda light chain antibodies shows negative kappa in casts that are lambda positive in serial section. Monoclonal light chain staining in atypical casts is characteristic of light chain cast nephropathy (LCCN). In this case, a monoclonal lambda clone is responsible though kappa light chains are the more common cause with a 3 to 1 predominance. These casts are not only tubulotoxic but are also obstructive.

Medullary Angiitis

The attached photomicrographs show the classic histopathology of renal medullary angiitis, a lesion involving the vasa recta of the medulla. The characteristic morphologic findings on renal biopsy include interstitial hemorrhage with associated polymorphonuclear leukocyte infiltration and karyorrhectic debris. Differentiation from acute tubulointerstitial nephritis is essential considering the very disparate etiologies, treatment, and prognosis. Medullary angiitis is most commonly seen in association with ANCA-associated disease but it has also been described in IgA nephropathy as well as in patients on antibiotics in the setting of infection (see ref below). It is an important lesson to recognize as it may be the only...

Waldenstrom Macroglobulinemia

In this image of a combined silver-trichrome stain, the arrow points to the abnormal material within the arteriole lumen. This material was positive for IgM and showed kappa light chain restriction by immunofluorescence, supporting the diagnosis of paraprotein. Interestingly, this kidney biopsy was taken from an 81-year-old man with acute renal failure who had been diagnosed with Waldenström macroglobulinemia (his bone marrow biopsy showed involvement by lymphoplasmacytic lymphoma and he had a circulating IgM-kappa paraprotein). A key point to remember is that monoclonal IgM paraproteins are associated with a wide spectrum of kidney diseases, including AL-type amyloidosis, cryoglobulinemic glomerulonephritis, and...

Obesity-Related Glomerulopathy

This biopsy is from a 61 year-old, morbidly obese patient, who presents with 6 month history of persistent proteinuria (UPCR: 3.7 gm/gm).  The displayed glomerulus is enlarged and shows an area of segmental sclerosis involving the perihilar region of the glomerulus. Additionally, electron microscopy showed only mild epithelial foot process effacement, and immunofluorescence was completely negative. All these morphologic features are supportive of a secondary (adaptive) form of focal segmental glomerulosclerosis (FSGS).  FSGS is a pattern of glomerular injury which may be primary or secondary.  One form of secondary FSGS is believed to be the result of glomerular hyperfiltration which...